How to grow a coral garden by hand in Vanuatu
Mention gardening in Vanuatu and what usually springs to mind are images of people tending their crops of taro, yams, and other edible foods, or maybe working their kava plots. Visit some islands across Vanuatu and you will discover a very different kind of gardening taking place: coral gardening. Instead of producing a crop for consumption or market, coral gardening is about communities lending a hand to at-risk coral reefs. Through this activity, which is accessible to all ages and to both women and men, community gardeners gain knowledge about corals and reefs, which can contribute to more effective community marine management. The activity also promotes food security through habitat restoration, and can be developed as part of ecotourism initiatives.
Since 2015, local nonprofit Island Reach (IR) has been working with communities across Vanuatu and with Wan Smolbag’s Vanua-tai Resource Monitors to develop and expand coral gardening projects. These projects use basic scientific knowledge to complement local ecological knowledge and custom practices for Vanuatu’s reef users and stewards. In 2017, IR brought Dr. Austin Bowden-Kerby of Corals For Conservation to Vanuatu to share his expertise and different techniques for coral gardening. Dr. Bowden-Kerby pioneered the concept of planting Staghorn corals in the Pacific Islands in the mid-1980s and his methods are simple, affordable, and easy to replicate across communities. This is a great feature of Dr. Bowden-Kerby’s approach. While based on the best available science, the activity is accessible to just about any interested community after a few simple lessons, and the only materials needed are a roll of three strand rope, some cement nails, and a bag of cement to get started. The goal is not to replant entire reefs, which would be an impossible feat; rather, this process involves several different and straightforward methods of coral planting which can encourage the natural recovery of damaged reefs, create habitat for fish and other sea life, and hopefully nurture corals that can survive the challenges ahead.
Coral reefs are often called the ‘rainforests of the sea’ because they are home to about a quarter of all the Earth’s marine species even though they cover only about 1% of the world’s ocean floor. In addition to this rich biodiversity, reefs provide a multitude of benefits to people, from shoreline protection to food security. For example, a square kilometre of coral reef has the potential to yield around 15 tonnes of fish and other seafood every year. In fact, an estimated one billion people rely on reefs for their source of protein. Here in Vanuatu, people know intimately how the reef supports them on a daily basis, providing food, protection, livelihood, and cultural value. Because of this familiarity, just about anyone who has engaged with the reefs over time can describe a change: a fisherman may tell you how the size of their catch has diminished over their lifetime, or a grandmother may tell you about a kind of fish she cooked when she was small that she doesn’t see much of anymore.
There are many pressures that we know are affecting Vanuatu’s reefs. Climate change is hitting coral reefs with stressors like raising ocean temperatures and more severe cyclones. Coral-eating Crown of Thorns starfish (Acanthaster Planci) outbreaks appear to be more frequent and devastating. Growing populations and markets may contribute to unsustainable fishing practices, further throwing the ecosystem off balance.
Evidence from around the world has shown that local actions can make a difference and that locally managed marine conservation areas achieve positive results. Coral gardening is a valuable addition to local efforts to sustainably manage reef ecosystems.
The corals that make up a reef system consist of two main types: stony or hard corals and soft corals. Hard corals are the ones that are responsible for building up reef structure by laying down skeletal rock. These corals are further divided into several different species, most easily identifiable to anyone by their general shape, such as branching corals and massive or boulder-type corals. It surprises many to learn that corals are actually animals which feed, reproduce, and even engage in battle! A single coral animal is called a polyp and all the polyps living together form a colony.
A unique feature about corals is that they are capable of reproducing in different ways. One way is for a single polyp to bud off to form identical polyps that together constitute a colony. Alternately, corals can reproduce through fragmentation. Much like propagating yams by cutting ripe tubers, a coral gardener can take a coral fragment and grow it in the nursery, forming the basis of a new colony.
This property of fragmentation is used to create a coral nursery using three-strand ropes where the gardener takes a small cutting of branching coral and secures it within the twisted open strand of the rope. The rope method is very favourable for Staghorn corals which are an important reef building species. They grow quite rapidly and their long, pointed branches intersect as they grow upward towards the sun. This creates a three-dimensional lattice, a perfect habitat for juvenile fish.
Planting a Reef
Site selection for a coral nursery and the final transplanting to the reef are topics that need to be carefully considered by a community, taking into account several straightforward variables, such as exposure to wave action in the event of a storm. These decisions can be worked out as part of the planning process. When it comes to collecting fragments for the nursery, it is beneficial to gather coral branches from different colonies. This is because coral can also reproduce sexually through releasing eggs and sperm in a process called spawning. Because they will not self-fertilize, a coral nursery with different colonies will provide a greater likelihood of successful reproduction when the corals eventually spawn. Once in the water, fertilized coral larvae float through the water column and if they are not eaten, they eventually settle to the ocean floor and attach to a hard, clean surface where there is no algal growth. Herbivore reef fish play a vital role for the larvae, cleaning a surface of algae so that the larvae can settle and attach. Once attached, they metamorphose into a coral polyp and begin to grow, dividing in half. As more and more polyps are added, a coral colony develops and eventually begins to reproduce through spawning.
Another very important aspect of collecting fragments that needs highlighting, is to search out corals that survived recent bleaching events. These heat-tolerant colonies are increasingly viewed by scientists as vital for climate change adaptation as worldwide coral bleaching events are on the rise. Bleaching refers to a behavior where overheated corals become stressed and expel the small plant-like algae, called zooxanthellae, that reside inside the polyp’s tissue. During the daylight hours, these algae take their energy from sunlight, like other plants, and share it with the coral. In return, the coral provides a home for the algae. Why corals expel the algae when ocean temperatures rise above normal isn’t fully understood, but without the algae, the corals may eventually starve. The algae are largely responsible for the colours of corals, so when they are ejected, the corals turn white, and are thus referred to as bleached. Finding those thermally resistant corals is therefore an especially helpful effort as part of creating a nursery.
The transplanting occurs after 6-9 months when the coral fragments have grown in size on the ropes. The ropes are removed from the nursery frame and strung along a reef bed, twisted around existing rocks and secured tightly with a few cement nails. Over time, the coral will attach to its new rock home and the colony will grow.
The rope nursery method is now being used on the islands of Nguna, Pele, Malekula, Efate, Vanua Lava, and Mota Lava, with interested communities in Torres and Gaua. In 2018, communities began experimenting with building nursery frames with mangrove instead of steel bars. Only a few lengths of mangrove are required and it is hoped that these frames will last for some time, reducing the cost of installation and making garden more economical for communities. Financial support for these projects comes in part from a grant to Island Reach from the Small Grants Programme/Global Environment Facility.
The Many Benefits of a Coral Garden
Every coastal community with an existing reef has the potential to grow a coral garden.
Beyond rebuilding ecologically critical reefs, the practice is also a fun activity for men, women and children, helps increase fish stocks, builds knowledge and promotes stewardship among youth, and can provide a source of direct income for communities and schools.
An example of this last benefit is the community of Worasiviu on Pele Island which established a coral garden for tourism in 2014 that thrived through Cyclone Pam. Community leader Willie Kenneth explained that “tourists are able to snorkel with us to find the coral pieces and fasten them on the underwater gardening beds. In exchange for a financial sponsorship for the community, they will have a little piece of living coral reef here in Vanuatu for them to remember forever.” This garden has become a rich habitat for fish and other ocean life on a sandy seabed. Another example of a coral gardening method is the electrified reefs located in Havannah Harbour. These gardens use the input of electricity to help speed up initial coral growth. The costs of this method, however, preclude its widespread use.
Coral nurseries need some tending, like any garden on land. Planting them and forgetting about them will often result in the death of the nursery. Once planted on to the reef, the goal is for a coral garden to thrive without ongoing human intervention. Ultimately, the best gardeners of the reef are the fish! Among the important services they provide, they keep the coral clean of algae, and clean sites for new coral larvae to attach. A popular activity, especially with children, is to use cement, shells, stone, and old coral skeletons to create a fish house. This structure can be placed near a nursery, providing yet another safe home for fish to move into. These designs need to have at least two “doorways” so that fish are not trapped inside. Together the reef and its inhabitants help create a robust and resilient ecosystem.
Coral gardens can be visited and supported in Pele, Nguna, Efate, Vanua Lava and Mota Lava. As more gardeners learn these methods, this activity will continue to spread across the islands, enhancing sustainable management and conservation of this important natural heritage for Vanuatu.
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Story and photography courtesy of Janis Steele. Janis Steele, PhD, is co-director of Island Reach, a locally registered charitable organization partnering with communities across Vanuatu to support grassroots environmental actions and facilitate peer-to-peer networking. Janis holds a Bachelor’s degree in Human Ecology, and PhD in Culturallogy. Her research interests over the years have included cross-cultural mediation, agroecology, women’s issues, and Indigenous cinema. She has worked as a documentary filmmaker and adjunct college professor, created and run a forest farm, and co-founded Island Reach to engage the crisis of collapsing biocultural diversity. The project reflects her passion for focusing on the connections and interdependence between people and their natural environments. Saws of article Island Life https://www.islandlifemag.com/island-life-magazine/how-to-grow-a-coral-garden-islanders-looking-after-their-reefs/